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Tropical Storm Norma Discussion Number 16
NWS National Hurricane Center Miami FL EP172017
300 AM MDT Mon Sep 18 2017
Norma is a small tropical cyclone, with one main curved band in the
eastern semicircle and an easy-to-find center. Dvorak estimates
are virtually unchanged from 6 hours ago and support the same
initial wind speed of 45 kt. Norma should begin to gradually
weaken later today as it moves over cooler SSTs and into a drier,
more stable airmass. The latest forecast is a blend of the
previous NHC prediction and the model consensus since guidance is
tightly clustered on the future weakening. Most of the global
models show convection disappearing within 2 days, so Norma is
now forecast to become a remnant low by that time.
Norma is now moving west-northwestward, continuing to be steered by
a ridge over northwestern Mexico. This general track is expected
for the next few days with a gentle curve toward the north-northwest
predicted as Norma moves around the southwestern portion of the
ridge. The new forecast is shifted westward, on the western side of
the model consensus closer to the ECMWF, which had the more offshore
track idea for some time before the bulk of the guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 18/0900Z 21.4N 111.8W 45 KT 50 MPH
12H 18/1800Z 21.5N 112.6W 40 KT 45 MPH
24H 19/0600Z 21.8N 113.6W 35 KT 40 MPH
36H 19/1800Z 22.2N 114.6W 30 KT 35 MPH
48H 20/0600Z 22.8N 115.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 21/0600Z 24.2N 115.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 22/0600Z...DISSIPATED
$$
Forecaster Blake
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